Sewn diaper with non-raveling stitching



United States Patent 3 Claims ABSTRACT OF THE DISCLOSURE A prefolddiaper formed of cut and folded woven fabric and having lines ofoveredge stitching extending along and over the cut edges of the foldedfabric to finish these edges and impart anti-ravel characteristicsthereto, each of the lines of stitching including a plurality ofinterlocking threads, one of which consists essentially of thermoplasticmaterial and at least one other of which is formed of non-thermoplasticmaterial. The thermoplastic thread of each line of stitching hasportions extending along one face of the fabric generally perpendicularto the edge and these portions are fused to the fabric and also to theinterlocking portions of the non-thermoplastic thread to anchor thestitching and prevent raveling thereof during normal use of the diaper.

The present invention relates to sewn articles, such as prefold diapers,and more particularly to non-raveling stitching for such articles.

In the formation of certain articles from sheet material, the stitchingthereof is well known for various and sundry purposes, including joiningseveral layers of sheet material together, the hemrning of pieces ofsheet material and the finishing of cut edges by overedging. Thisstitching is usually formed by a sewing machine and has portionspenetrating through the sheet material and interlocking with otherportions thereof on at least one side or face of the sheet material.

Such stitching is subject to raveling during use of the sewn article,particularly at the terminal end portions thereof, and this ravelingproblem becomes acute with articles, such as prefold 'diapers, which aresubjected to frequent and repeated laundering. As is well known, prefolddiapers are formed by folding a section of diaper fabric into a size andshape adapted to fit an infant without additional folding. The foldeddiaper has at least one line of stitching penetrating therethrough tosecure the same in this folded condition and frequently the cut edges ofthe diaper fabric are finished by overedge stitching.

Various attempts have been made to stabilize this stitching to preventraveling thereof, and such attempts have included an operation usuallyreferred to as tailing wherein the stitching is continued for somedistance outwardly from opposite extremities of the sewn article to forma tail of interlocked threads. Such tails, however, ravel after only afew launderings and, therefore, have not effectively stabilized thestitching.

A procedure commonly referred to as backtaoking has also beenextensively used to reduce the raveling of stitching and is accomplishedby reversing the sewing machine feed means adjacent each edge of thearticle to form a short line of reverse stitching adjacent each end ofthe stitching. While being moderately successful at reducing theraveling problem, such backtacking is very time consuming and laboriousand adds considerably to the cost of manufacture of sewn articles.

Recently, another attempt at a solution to this raveling problem hasbeen proposed. This proposed solution necessitates a special type ofthread in the stitching, which thread is formed of a multiplicity ofhighly crimped fila- 3,424,161 Patented Jan. 28, 1969 ments. During thesewing'operation, this thread is under tension so that the crimp istemporarily removed from the filaments. However, when the thread is cutat the edges of the article, the filaments relax to restore the crimpand the thread blossoms out and intertwines to form an enlarged portionor fluffy ball at the end thereof, which prevents the thread from beingpulled back through the fabric to prevent raveling of the stitching.

It is, therefore, an object of the present invention to provide a sewnarticle having one or more lines of stitching which may be of anydesired type and which are anchored against raveling even after repeatedlaundering.

A more specific object of the present invention is to provide a sewnarticle of the character described wherein the stitching includes anessentially thermoplastic thread which is fused to the article atselected areas of the article including terminal end portions of thestitching to anchor the stitching and prevent raveling thereof.

A further more specific object of the invention is to provide, in a sewnarticle, a line of stitching anchored against raveling by having athermoplastic sewing thread thereof fused to interlocking portions ofitself or another cooperating sewing thread of the line of stitching.

A still more specific object of the invention is to provide, in a sewnarticle, a line of stitching anchored against raveling by athermoplastic sewing thread thereof being fused to the sewn article andto interlocking portions of itself or another cooperating sewing thread.

Some of the objects of the invention having been stated, other objectswill appear as the description proceeds when taken in connection withthe accompanying drawings, in which FIGURE 1 is a perspective view of aprefold diaper incorporating the features of the present invention;

FIGURE 2 is a fragmentary, enlarged perspective view of the corner ofthe diaper enclosed within the rectangle 2 in FIGURE 1;

FIGURE 3 is a view similar to FIGURE 2 of the 0pposite corner enclosedwithin the rectangle 3 in FIG- URE l;

FIGURE 4 is an enlarged, fragmentary, somewhat schematic perspectivedetail of the stitching extending along opposite ends of the diaper ofFIGURE 1;

FIGURE 5 is an enlarged, fragmentary, perspective view of a sewn articleincluding another type of seam incorporating the features of the presentinvention; and

FIGURE 6 is a fragmentary, enlarged, somewhat schematic perspective viewof a portion of the seam shown in FIGURE 5.

Referring now more specifically to the drawings, there is shown inFIGURE 1 a diaper 10 of the type commonly referred to as prefolddiapers, and which is representative of sewn fabrics or articles whichmay be produced in accordance with this invention. This diaper is formedof fabric 11 which is folded into a size and shape, usually rectangular,adapted to fit an infant.

Diaper 10 has a pair of spaced apart lines of stitching 12, 13 eachbeing preferably continuous and penetrating through the folded fabric 11and extending longitudinally of the diaper 10 to secure the fabric 11 infolded condition. Lines of stitching 12, 13 may be of any type ofstraight seam conventionally formed by sewing machines.

Opposite end edges of diaper 10 have suitable lines of preferablycontinuous stitching 14, 15 of the conventional overedge type extendingtherealong and thereover to finish these edges and prevent raveling ofthe fabric therealong and to aid in holding the fabric in the foldedcondition. This overedge stitching is more particularly shown in FIG-URES 2, 3 and 4, which are enlarged details of the line of overedgestitching 14.

This stitching is illustrated as being formed by three (3) threads, eachof which follows a separate course in the stitching, but it should beunderstood that the same may be formed of any desired number of threadsin any desired arrangement without departing from the scope of thisinvention. In the illustrated form, stitching 14 includes a needlethread 16 which is disposed inwardly from the end edge of fabric 11 andhas first portions 17 extending along one face of fabric 11 and secondportions 18 penetrating through the fabric to the opposite face thereof.Portions 18 are in the form of loops having legs 18a extending throughthe fabric and bights 18b disposed on the opposite face thereof.

Stitching 14 also includes a first looper thread 20 having firstportions 21 extending along and parallel to the end edge of fabric 11and second portions 22 extending along the aforesaid one face of thefabric 11 and inwardly from and generally perpendicular to the end edgethereof. Second portions 22 are in the form of loops having legs 22a andbights 22b connecting the inner ends of the legs of each loop. The loopportions 18 of the needle thread 16 penetrate through the loop portions22 of first looper thread 20 to interlock the two threads.

A second looper thread 23 cooperates with needle thread 16 and firstlooper thread 20 to form the stitching 14. Thread 23 includes firstportions 24 extending along the aforesaid opposite face of the fabric 11and inwardly from and parallel to the end edge thereof, and secondportions 25 extending outwardly from the portions 24 to the end edge.Portions 25 are in the form of loops having legs 25a penetrating throughthe loop portions 18 of the needle thread 16 to interlock the needlethread and second loo er thread, with bights 25b connecting the outerends of the legs 25a outwardly of the end edge of the fabric 11. Thelegs 22a of the loop portions 22 of first looper thread 20 penetratethrough the loop portions 25 of second looper thread 23 to interlock thetwo looper threads.

In accordance with the present invention, lines of overedge stitching 14and are each formed of at least one thread consisting essentially of amaterial, such as a thermoplastic material, capable of being fused tothe fabric 11 to anchor the thread to the fabric and to prevent ravelingof the stitching. An example of a thermoplastic thread which has beenused successfully in accordance with this invention is polypropylene,but it should be understood that other thermoplastic threads, includingblends or combinations of thermoplastic and non-thermoplastic fibers,may be used. Also, it is preferred that the thermoplastic thread bemulti-filament rather than mono-filament because of the increasedpliability thereof and therefore increased handling ease in sewing.

While more than one of the threads in the stitching may bethermoplastic, it has been determined that a single thermoplastic threadis usually sufiicient, and the remainder of the threads preferably areformed of non-thermoplastic material to avoid any undue stiffening inthe stitching and to maintain suppleness in the line of stitching. Inmost instances, this thermoplastic thread is preferably a looper threadsince the looper thread usually has a greater portion thereof exposed onthe surface of the fabric than the needle thread, to thus have a greaterarea for being anchored to the fabric by fusing. Also, due to the looperthread usually being disposed substantially on one side or face of thefabric, the same is more readily subjected to heat for fusing. Further,the looper thread usually engages the needle thread and other threads,if any, on the same side of the fabric to thus be fused to these threadsas well as the fabric to provide a more secure anchor for the stitching.

While it has been determined that the thermoplastic thread in thestitching may be fused to the other cooperating sewing threads or tointerlocking portions of itself without being fused to the fabric tosufficiently anchor the stitching and prevent raveling thereof witharticles requiring infrequent or gentle laundering, it is generallypreferred that the thermoplastic thread be fused to the fabric toprovide a broader and greater area of anchorage to the line ofstitching. For maximum anchorage of the line of stitching in accordancewith the invention, the thermoplastic thread should be fused to both thefabric and other sewing threads or itself, which is preferred for manytypes of sewn articles requiring repeated and frequent launderings.

As illustrated in FIGURES 2-4, first looper thread 20 of each of thelines of stitching 14, 15 is formed of thermoplastic material, such aspolypropylene, and needle thread 16 and second looper thread 23 areformed of nonthermoplastic material, such as cotton. First looper thread20 is fused to the fabric 11, and preferably also to the needle thread16 and second looper thread 23, at selected areas of the fabricincluding the terminal end portions of the stitching at all four cornersof diaper 10, two of which are indicated at 26, 27 in FIGURES 2 and 3.The fused portions 26, 27 of the thermoplastic thread extend inwardlyfrom the ends of the stitching for a predetermined distance sufficientto encompass a plurality of stitches for a plurality of the loopportions 22 of looper thread 20 to be fused to the fabric 11.

The fusion of the thermoplastic thread to the fabric is preferablyaccomplished by the application of heat thereto sufficient to soften thethermoplastic thread and cause the same to become tacky and to fixedlyadhere to the fabric and preferably also to adhere to the other threadsof the stitching.

Referring now to FIGURES 5 and 6, there is illustrated therein anothertype of stitching incorporating the features of the present invention.This stitching is commonly referred to as chain stitching and hasperhaps the greatest propensity to ravel of all standard types ofstitching.

This chain stitching usually is formed of a single thread 30 which hasportions 31 extending along and in engagement with one side or face ofthe fabric and loop portions 32 penetrating through the fabric andinterlocking with each other on the opposite side or face of the fabric.

In accordance with the present invention, thread 30 consists essentiallyof a thermoplastic material, such as polypropylene, and is fused to thefabric on the side or face thereof having the interlocking loop portions32 thereon and at selected areas of the fabric including terminal endportions of the stitching, as is indicated at 33, 34. The fused portions33, 34 of thread 30 preferably extend for a predetermined distanceinwardly from opposite ends of the stitching sufficient to encompass aplurality of stitches. As indicated above, the loop portions 32 are alsopreferably fused to each other to further anchor the stitching andprevent raveling thereof.

The lines of stitching 12 and 13 in diaper 10 may be of this chainstitch type and may be anchored by fusing, as illustrated in FIGURES 5and 6, or may be anchored by the overedge stitching 14, 15 withoutfusing. However, these lines of stitching 12, 13 are usually of the lockstitch type and the overedge stitching 14, 15 is sufficient to anchorthe same againstraveling, although such lock stitching may include athermoplastic thread and be fused to prevent raveling in accordance withthe present invention if desired. In this latter respect, there are manyprefold diapers, such as the diaper shown in US. Patent No. 3,150,693,which are folded and stitched with lines of stitching similar to thelines of stitching 12, 13 without any overedge stitching. In such cases,the lines of stitching securing the diapers in folded condition shouldinclude a thermoplastic thread fused in accordance with the presentinvention.

Further, while the present invention has been described in connectionvwith and has particular utility with prefold diapers due to thefrequent and repeated laundering to which diapers are subjected, itshould be understood that the present invention is not limited theretobut has application to a wide variety of garments and other sownarticles.

It is, therefore, believed apparent that a novel nonraveling stitchingfor sewn articles is provided by the present invention wherein thestitching is anchored against raveling by a thread thereof being fusedto the article at selected areas thereof and preferably additionallyfused to interlocking portions of itself or other cooperating se-wingthreads.

In the drawings and specification there have been set forth preferredembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation, the scope of the invention being defined in theclaims.

I claim:

1. A prefold diaper formed of woven fabric cut and folded into a sizeand shape adapted to fit an infant and having lines of overedgestitching extending along and over the cut edges of the folded fabric tofinish these edges and impart anti-ravel characteristics thereto, eachof said lines of stitching comprising a thread consisting essentially ofthermoplastic material and at least one additional thread ofnon-thermoplastic material interlocking with said thermoplastic thread,said thermoplastic thread having portions extending along one face ofthe fabric generally perpendicular to the edge of the fabric, and saidportions being fused to the fabric and also to the interlocking portionsof the non-thermoplastic thread only at the corners of the diaper toanchor the stitching and prevent raveling thereof during normal use ofthe diaper without undue stiffening of the edges of the diaper.

2. A prefold diaper according to claim 1 wherein there are twonon-thermoplastic threads in each line of stitching and saidthermoplastic thread is a looper thread.

3. A prefold diaper formed of woven fabric cut and folded into a seizeand shape adapted to fit an infant and having lines of overedgestitching extending along and over the cut edges of the folded fabric tofinish these edges and impart anti-ravel characteristics thereto, eachof said lines of stitching comprising a needle thread penetratingthrough said fabric in spaced relation to the edge thereof and a pair oflooper threads which interlock with each other at the edge of the fabricand also interlock with said needle thread on opposite sides of thefabric, one of said looper threads and said needle thread being formedof non-thermoplastic material, and the other looper thread consistingessentially of thermoplastic material and being fused to the fabric andalso to the interlocking portions of said non-thermoplastic needle andlooper threads to anchor the stitching and prevent raveling thereofduring normal use of the diaper.

References Cited UNITED STATES PATENTS 3/1964 Jamison 128-284 8/1967Kuhn 15693

